DE2453231A1 - LOW-PILLING POLYESTER FIBERS - Google Patents

Description

Bayer Aktiengesellschaft

Central area of patents, trademarks and licenses

509 Leverkusen. Bayerwerk

Sdt / Wn.

- a NOV. \ 97k low pilling polyester fibers.

The invention relates to textile fibers made from high molecular weight linear polyesters with a reduced tendency to pilling.

The best known and technically most important representative of polyesters, which are used for the production of textile fibers, is polyethylene terephthalate. It is obtained by polycondensation of terephthalic acid or its derivatives with glycol. The threads produced therefrom by the melt spinning process are usually bundled, drawn in hot water, fixed in hot air, crimped and cut. The fibers produced in this way normally have a strength of 2.5 to 4.5 p / dtex, an elongation of 20 to 50 % and a boiling shrinkage of 0 to 3 %.

_{Textiles with, for example,} excellent wear properties, such as low susceptibility to creasing, low water absorption and therefore easy drying or high strength and good abrasion resistance, can be produced from these fibers.

The high strength and good abrasion resistance of the polyethylene terephthalate fibers produced textiles have the disadvantage that e.g. items of clothing such as suits or sweaters, have an increased tendency to take pills, which significantly limits their usability.

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Pills or piling are understood as the image of small kftötchen or pills on the surface of the garment. They arise from the fact that fiber ends or loose fiber parts sticking out of the surface tangle and because of the good strength of the fibers, they do not fall off, but stick to the surface. A mechanical one Removing the nodules, such as brushing or clipping, is available very complex and expensive and also has little success because new pills are constantly being formed.

There is therefore a need to modify the fibers so that the pills are released when the garment is worn fall off by itself.

Many attempts have been made to this end. It has, for example, tried the strength or _o scrub resistance of the polyethylene terephthalate staple fibers reduce characterized in that spun polyester and has processed whose molecular weight compared to the commonly used polyester was lower "In this case, however, other disadvantages resulted, for example, difficulties arise because of the low melt viscosity during spinning (reduced performance in single-screw extruders), which is also expressed in large fluctuations in titre. In addition, the abrasion resistance is so greatly reduced that white, milky surfaces become visible in the more heavily stressed areas of the dyed textiles. They arise because the fibers are roughened when they are rubbed due to their greater brittleness. The resulting abrasion and the increased scattered light make these areas appear brighter.

In addition, staple fibers made of polyethylene terephthalate with a reduced molecular weight can be used for dyeing with carriers dye less well than staple fibers made of polyethylene terephthalate with normal molecular weight, so that the miscibility of these is limited to both fiber types.

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It has now been found that polyethylene terephthalate staple fibers can be used with the usual properties in terms of strength, elongation and boiling shrinkage, but greatly reduced tendency to Pills are obtained if, in the production of the polyester, 0.01 to 2.00 wt. #, Preferably 0.30 to 0.90 wt. #, Diphenylsilanediol, based on dimethyl terephthalate, is added and the thread-forming polymer has a relative value after spinning Viscosity of 1.53 to 1.7o, preferably 1.55 to 1.63, has. In the context of this application, the relative viscosity the ratio of the viscosity of an oily solution of polyethylene terephthalate in o-chlorophenol means the viscosity of the pure o-chlorophenol, measured in equal units at 25 ° C.

The invention, therefore, fibers of vast proportions of polyethylene terephthalate units containing high molecular weight polyesters, wherein the polyester.% Diphenylsilanediol contain from 0.008 to 1.6 wt.

This gives these fibers by vast proportions polyethylene terephthalate spun-containing high molecular weight polyester containing 0.008 to 1.6 wt. # Diphenylsilanediol, the filaments thus obtained in a water bath at temperatures of 50 to 98 ⁰ C, preferably from 80 to 95 ⁰ C, stretched and puckered in a known manner and cut into stacks.

It was found to be a significant advantage that the extruder performance during spinning despite the somewhat lower molecular weight is not less than with normal polyethylene terephthalate and the polyester changes when dyeing with carriers can be stained just as deeply as normal material.

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Another advantage of this process is that the polyester can also be spun as granules and not necessarily continuously must spin. Another advantage has been found to be that the addition of diphenylsilanediol increases the speed the polycondensation increases, i.e. the required molecular weight can be achieved in a shorter time, so that the Reduce production costs.

The polyester suitable for spinning is obtained by adding 0.01 to 2.00 wt. ^, Preferably 0.30 to 0.90 wt It has been shown that about 8θ fo the diphenylsilanediol is contained in the finished polyester afterwards, it being assumed that it is largely chemically bonded as a chain segment with the formula

is present in the polyester. The Si-0 bond is a weak point in the polymer chain because it is broken in the presence of water will. It has been found that in the present case the bond is susceptible to hydrolysis, but it is nonetheless in contrast to other known processes without a noticeable hydrolytic degradation, which is possible after the Polycondensation resulting polymers from an autoclave in water in coarse titers to spin and to granulate The relative viscosity of the granulate obtained in this way is exactly the same as the relative viscosity of a melt block that is spun in air became. The reason for this relatively low susceptibility of the granulate to hydrolytic degradation is likely to have two causes have: on the one hand, the spun coarse-denier monofilament is very compact with a relatively small surface area, based on

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the volume, so that only a few Si-O bonds with water in Come into contact; on the other hand, the two relatively large phenyl rings should provide a certain steric protection for the Si-O bond form.

Only during the stretching of the fine denier filaments in a water bath in the temperature range of 50 to 98 ⁰ C, preferably from 80 to 95 ⁰ C, a portion of the Si-O bonds is cleaved hydrolytically and it enters a certain molecular degradation. This is understandable because with a titer of, for example, 3.3 dtex, there is a very large surface area in relation to the volume and many Si-O bonds come into contact with water. This breaking of the few Si-O bonds is sufficient to make the staple fibers pill-resistant. The relative viscosity of the thus treated staple fibers is usually between 1, ² H and 1 ^ 7 depending on the content of diphenylsilanediol, when the threads before stretching have a relative viscosity of 1.53 to l * 7o.

It has been found that a lower content than 0.008 wt.% Does not lead to diphenylsilanediol to pillresistenten staple fibers, because the molecular weight reduction then is too low.

A larger amount of Diphenylsilanediol as Ι, βο wt.% Involves difficulties in the polycondensation because be reached by low melt viscosities. In addition, the molecular degradation in the drawing bath is so strong that no usable item of clothing can be produced from the staple fibers produced in this way.

For the purposes of the present patent application, the term polyesters containing predominant proportions of polyethylene terephthalate is to be understood as meaning not only the pure homopolymer of terephthalic acid and ethylene glycol, but also copolyesters, but at least 90 % of these consist of recurring units of the formula

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(ο

exist. In addition to terephthalic acid, these copolyesters can also contain isophthalic acid, hexahydroterephthalic acid and also subordinate ones Contain amounts of aliphatic dicarboxylic acids, such as sebacic acid or adipic acid. In addition to ethylene glycol come butanediol or 1,4-bis (hydroxymethyl) cyclohexane, for example, are also possible as glycol components.

The reduced tendency to pill can be determined in the laboratory test according to ASTM test standard D 1375-64 (Tests for Pilling Resistance of Textile Pabrics-Part F-Random Tumble Pilling Tester). For the test, the staple fibers to be examined were twisted and processed into flat knitted fabrics. The grading of the individual samples are based on the following scale

Grade 5 excellent resistance (no pilling) ability

Grade 4 good resistance (light pilling) Grade 3 medium resistance (medium pilling) Grade 2 low resistance (heavy pilling)

Grade 1 very low resistance (very strong

pilling)

Staple fibers made from a polyester which has a content of 0.008 to Ι, βο wt. $., Preferably 0.30 to 0.90 wt. % Diphenylsilanediol, and a relative viscosity of 1.53 to 1.7o, preferably 1 , 55 to 1.63, show a pill rating of 4 to 5 * while staple fibers

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made of pure polyethylene terephthalate with a relative viscosity of e.g. 1.65 have a pill rating of 1 to 2.

It was extremely surprising that the polyethylene terephthalate granulate with a content of 0.008 to Ι, βο wt. Preferably 0.150 to 0.90 wt. ^, Diphenylsilanediol and a relative viscosity of 1.53 to 1.7o, preferably 1, 55 to I, 6j5, does not cause the extruder to perform poorly compared to normal polyethylene terephthalate. This is because the melt viscosity of the claimed polyethylene terephthalate is 100 to 200 % higher with the same relative viscosity as a homopolymer (measurement of the melt viscosity using the cone-plate method, Rotovisko device from Gebrüder Haake, Berlin; temperature 28o ° C, without nitrogen flow, heating time 3 min).

For example, the following was measured:

rel. Melt viscosity Viscosity at 280 ° C

pure polyethylene terephthalate 1.60 1000 poise

Polyethylene terephthalate

+ 0.80 wt.% Diphenyl Ι.βΟ 2200 poise

silanediol «

The relative viscosity indicated in the examples was measured as indicated on page j5.

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Example 1 :

Prior to the reaction of dimethyl terephthalate with ethylene glycol to the reaction mixture 0.70 wt.% Diphenylsilane diol, based on dimethyl terephthalate, was added. The transesterification occurs during three hours at 200 ⁰ C.Sodann precondensation is carried out at a temperature of 275 "^ within 1.5 hours. This temperature is maintained for the polycondensation, whereby the pressure to about 1 Torr is reduced. The The polycondensation is over after 1.6 hours, and then spun from the autoclave in water to form a coarse monofilament and granulated had a diphenylsilanediol content of 0.56% by weight.

The granulate is spun using the technique of melt spinning through a multi-hole nozzle into threads with a single titer of 10 dtex and wound up at a speed of 1100 m / min. The strands are doubled to form a tow of 100,000 dtex, in hot water at 9O ⁰ C and then in a Dämpfkanal in the ratio of 1: stretched 3,2o, crimped in a Stauchkammerkräusel, energized in hot air dried and then to staple fibers of 60 mm in length. The fibers show a strength of 3> 3 p / dtex, an elongation of 35 % and a boiling shrinkage of 1 %. The titer is 3.3 dtex and the relative viscosity is 1.45.

Yarns with a left twist were made from the staple fibers of 495 turns / m and a right turn of 310 turns / m and which subsequently become a Flat knitted fabrics were processed. This knitted fabric was subjected to the laboratory pill test according to ASTM test standard D 1375-64 and achieved the excellent after 120 minutes of testing

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Pill note 5, i.e. no pilling.

If you compare the staple fiber just described with a staple fiber made from pure polyethylene terephthalate the same relative viscosity of 1.57 and the textile properties of the staple fiber described above is completely the same, the knitted fabric made from these staple fibers in the laboratory pill test shows the test duration after 120 minutes Grade 2 on, i.e. heavy pilling.

Fabrics were made from the staple fibers, made from a polyester with a content of 0.56 wt. The pants showed a completely different picture after a test of 280 hours. The trousers made of staple fibers with the addition of diphenylsilanediol showed no pills or very little pills in a few places, while the trousers made of pure polyethylene terephthalate showed a very annoying pill. The wearing test thus confirms the findings already obtained in the laboratory test. · '-

Example 2;

Before the transesterification of dimethyl terephthalate with fithylenglykol to the reaction mixture O, 6o wt.% Diphenylsilane diol, based on dimethyl terephthalate, was added. The transesterification takes place in an autoclave at a temperature of 200 ° for a period of J> hours. The following pre-condensation takes 1.6 hours at 275 ⁰ C. In order to polycondensation at 275 ° C, the pressure is reduced to 1 torr. It is over after 1.7 hours, so that it is then spun in water and granulated. The granulate has a relative viscosity of 1.59 and a melt viscosity of 2200 poise at 280.degree. It has a diphenylsilanediol content of 0.48%.

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The granulate is spun using the melt spinning technique through a multi-hole nozzle into threads with a single titer of 10 dtex and wound up at a speed of 1100 m / min. The strands are doubled to form a tow of 100,000 dtex, in hot water of 90 ⁰ C and then in a Dämpfkanal in the overall ratio 1: stretched 3.20, crimped in a Stauchkammerkräusel, energized in hot air dried and then to staple fibers of 6o mm Cut length.

The fibers show a titer of 3.3 dtex, a strength of 3.4 p / dtex, an elongation of 37 %, a boiling shrinkage of 0 % and a relative viscosity of 1.46.

Yarns with a left twist of 495 turns / m and a right twist were produced from the staple fibers of 310 twists / m and which were then processed into a flat knitted fabric. This knit was the Laboratory pill test according to the above-mentioned ASTM test standard D 1375-64 and achieved the excellent pill rating of 5, i.e. no pilling, after a test duration of 120 minutes.

If one compares the staple fiber just described with a fiber made from polyethylene terephthalate with the same addition of 0.6o wt. % Diphenylsilandiöl but a relative viscosity of the granulate of 1.75, this shows a slightly higher strength and otherwise the same textiles Properties in the laboratory pill test according to ASTM test standard D 1375-64 after 120 minutes of test duration the pill grade 2, ie strong pilling.

On the other hand, a polyester with the same diphenylsilanediol content but a Assuming a relative viscosity of 1.5o, so strong a molecular degradation occurred during the stretching that No serviceable garment could be made from the fibers.

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Claims (1)

245323Ί - Αι « Claims; 1.) Pipes from high molecular weight polyesters containing predominantly proportions of polyethylene terephthalate units, characterized in that the polyesters Ο, ΟΟδ to 1.6% by weight . Contain diphenylsilanediol. 2.) Pasern according to claim 1, characterized in that the Polyester to at least 90 wt. # From recurring structural units the formula ..0C - // NyCO-O-CH ₂ -CH ₂ -O- consist. 5.) Paving according to claim 1 or 2, characterized in that the polyesters have a relative solution viscosity - ^ _re n » measured at 25 ° C in a l ^ igen solution in o-chlorophenol of 1.4l to 1.47. 4.) from parsers are predominant proportions Polyäthylenterephthalateinheiten containing high molecular weight polyesters, characterized in that the polyesters by transesterification of a reaction mixture consisting essentially of dimethyl terephthalate, and 0.01 A'thylenglykol feis 2 wt.% Diphenylsilane diol, based on the amount of dimethyl terephthalate, and subsequent polycondensation were obtained « 5.) Process for the production of fibers from high molecular weight polyesters by spinning the melt of a high molecular weight polyester containing predominantly proportions of polyethylene terephthalate units, stretching in a water bath at temperatures of 50 to 98 ⁰ C and subsequent processing into staple fibers of the threads thus obtained, characterized in that one Spun polyester containing 0.008 to 1.6 wt. $ Diphenylsilanediol. le A 16,095 - 11 - 609820/1098 6.) A process for the production of fibers from high molecular weight polyesters by spinning the melt of a high molecular weight polyester containing predominantly proportions of polyethylene terephthalate units, drawing in a water bath and subsequent processing into staple fibers of the threads thus obtained, characterized in that a reaction mixture consisting essentially of dimethyl terephthalate, ethylene glycol, 0.01 to 2% by weight of diphenylsilanediol., based on the amount of dimethyl terephthalate, is transesterified in a known manner, polycondensation and spinning the polyester thus obtained, the yarns thus obtained in a water bath at temperatures of 50 to 98 ⁰ C. stretched and processed into staple fibers. 7.) The method according to claim 5 or 6, characterized in that the threads after spinning and before Stretch have a relative viscosity of 1.53 to 1.7o. 'Le A 16,095 - 12 - 609820/1098